class_docstr: Context manager for working directory.
  
  Parameters:
      dir (str): new working directory
code: def __enter__(self):
      self.old_dir = os.getcwd()
      os.chdir(self.dir)
  
imports: from __future__ import print_function, absolute_import
  import os
  import sys
  import logging
  import tempfile
  from time import time
  from functools import wraps
  import numpy
label_desc: Use image node_id 2 for calling the chdir obj's underlying member method code with example usage: obj.__enter__() without return types